Known photopolymerisable systems contains photoinitiators characterised by the presence, within the molecule of a functional group that, by electromagnetic excitation, generally UV radiation, is able to generate radicals.
These compounds are described for example in U.S. Pat. No. 3,715,293, DE 2722264, EP 161463, EP 3002, EP 88050, EP 284561, EP 192967, EP 850253 and are usually used in the polymerisation of unsaturated ethylene systems.
In order to obtain a good polymerisation, both in surface curing and in through curing it is a common practice to associate within the formulation different photoinitiators.
In our previous patent U.S. Pat. No. 6,492,514 we described compounds containing within the same molecule two different active functional groups, both able to generate radicals by a photochemical process and showing high activity as photoinitiators.
These molecules can generate surprising synergies in comparison with the use of two photoinitiators each containing one of the two functional groups.